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  • Extreme Precipitation‐Tempe...
    Najibi, Nasser; Steinschneider, Scott

    Geophysical research letters, 28 July 2023, Letnik: 50, Številka: 14
    Journal Article

    The sensitivity of atmospheric river (AR)‐induced precipitation to climate change is primarily driven by increases in atmospheric water vapor with warming. However, the rate at which AR‐based precipitation intensifies with warming and whether this rate differs from non‐AR events remains uncertain. This work uses multiple statistical models to estimate regional, extreme precipitation‐temperature scaling rates in California for AR and non‐AR events. Scaling rates are determined using cold‐season daily and hourly precipitation, along with multiple temperature variables to assess robustness of the results. We find that regional scaling rates for ARs are consistently larger than non‐ARs, especially for hourly event maxima (posterior median scale rates of 5.7% and 2.4% per °C for ARs and non‐ARs, respectively). ARs remain near saturated (i.e., high relative humidity) and exhibit more lift and a stronger increase in specific humidity aloft with warming as compared to non‐ARs, helping to explain the difference in precipitation‐temperature scaling rates. Plain Language Summary Atmospheric rivers are long and narrow conveyor belts of water vapor in the sky that transport moisture in the lower atmosphere. They often cause extreme precipitation that can cause flooding along the west coast of the United States. The rate of intensification of atmospheric river‐based precipitation with warming is a fundamental scientific question with important implications for adapting civil infrastructure to climate change. This study aims to quantify the relationship between atmospheric river‐based extreme precipitation and temperature, and to determine how it differs from other precipitation events. To do so, we utilize multiple statistical methods to quantify cold‐season precipitation‐temperature scaling rates at weather stations across California. In our analysis, we consider different temperature variables, timescales of data, and ways of accumulating precipitation during events to determine the robustness of our results. Overall, we find that extreme precipitation increases faster with warming during atmospheric rivers compared to other types of events. This difference is linked to the fact that atmospheric rivers exhibit a more direct increase in moisture content and lift with warming. These results suggest that extreme precipitation during atmospheric rivers will increase faster than other events as temperatures rise in the future, which could accelerate damage linked to future flooding events. Key Points Precipitation‐temperature (P‐T) scaling rates during atmospheric rivers (ARs) are larger than other precipitation events in California P‐T scaling rates for AR‐based events approach the Clausius‐Clapeyron rate (7% per °C) when using dew point temperature The differences in P‐T scaling rates for ARs versus non‐ARs are linked to the sensitivity of moisture content and lifting mechanism to warming